Canara Bank — not updating my signature

Address: Bangalore, Karnataka

I am holding my sb account in canara bank, hennur branch. I gave request for updating my signature in 2016. After receiving my cheque book i issued 4 cheques.2 cheques bounced back saying difference in signature. A balance 2 cheques gone for clearing. The first 2 cheques which were bounced were charged fine of rs 500 per cheque. Why i should loose my money for the irresponsibility of the bank officials. Kindly help me out.